Strange things happen to time when you travel, because the earth is divided into twenty-fo

ur time zones, one hour apart. You can have days with more or fewer than twenty-four hours, and weeks with more or fewer than seven days.

If you make a five-day trip across the Atlantic Ocean, your ship enters a different time zone every day. As you enter each zone, the time changes one hour. Traveling west, you set clock back; traveling east, you set it ahead. Each day of your trip has either twenty-five or twenty-three hours.

If you travel by ship across the Pacific, you cross the International Date Line. By agreement, this is the point where a new day begins. When you cross the line, you change your calendar one full day, backward or forward. Traveling east, today becomes yesterday; traveling west, it is tomorrow.

Strange things happen to time when you travel because______.

A．no day really has twenty-four hours

B．the earth is divided into time zones

C．time zones are not all the same size

D．no one knows where time zones begin